Packaged explosive



Oct. 14,1969 pow 3,472,166

PACKAGED EXPLOS I VE Filed Feb. 8, 1968 United States Patent PACKAGED EXPLOSIVE Thomas P. Bowling, Fullerton, Pa., assiguor to 'Cornmercial Solvents Corporation, New York, N.Y., a corporation of Maryland 1 Filed Feb. 8, 1968, Ser. No. 704,037 lint. Cl. F42!) 3/00 US. Cl. 10224 23 Claims ABSTRACT OF THE DISCLOSURE A packaged explosive is provided comprising a flexible container filled with a deformable explosive. A force distributing plate having an aperture or well for receiving and positioning a pusher pole is located in the bottom end of the container. A fuse is also located within the container and held therein by the plate. When the pusher pole is inserted into the container, and into the well or aperture of the bottom plate, the force applied to position the packaged explosive at the blast site is distributed by the bottom plate to the explosive and then via the explosive, to the walls of the container.

This invention relates to packaged explosives particularly of the type known as bombing charges.

In mining operations and particulary in mining operations such as block caving and sub-level stopping, the ore chute often becomes blocked with large boulders or rock fragments which usually become wedged into position blocking the chute. Such blockages are extremely difiicult to remove. Heretofore, in order to remove such a blockage the practice has been to detonate a bagged explosive charge known as a bombing charge placed adjacent the blockage between the boulder and the chute wall to blast the chute clear. The bombing charge is a pliable or deformable explosive such as a granular explosive, a plastic gel, or a thick slurry in a relatively flexible bag. A long wooden pusher pole is inserted into the package through the rear end of the bag, and the bombing charge is then jammed between the wall and the boulder or rock fragment to be moved. Several such packages are positioned around the boulder to provide a sufiicient explosive force to dislodge it.

One difficulty with this procedure has been that when the wooden pole is forced against the inside of the package wrapper to push the package tightly into place, the pole often pierces the front end of the bag, after which it is no longer possible to move the charge, and the explosive can leak from the package through the resulting hole.

Other difiiculties have arisen in the initiation of the explosive bombing charge. When cap-sensitive explosives are used, a detonating cord such as Primacord, is wrapped around the bombing charge, and the charge is then jammed in position.

Slurries are initiated by a length of detonating fuse within the package. The cord is run out of the front end of the bombing charge, and around the exterior of the package. In either case, the detonating cord can be abraded against the wall, and can snag on the jagged walls of the chute or on the boulder. This can result in the cord being broken, damaged, or dislodged.

The instant invention provides a packaged explosive particularly suited for use as a bombing charge in which means are provided for transmitting the force applied by the pole to the explosive composition in the bag, and thence via the explosive composition to the bag walls, rather than directly to the bags, thus preventing pusher pole from breaking through the bag. The packaged explosive of this invention also provides a means for posiis placed into position.

In accordance with this invention, a packaged explosive of the category described above is provided comprising a generally flexible container; a deformable ex plosive therein; a force-distributing bottom place disposed in the container for receiving and positioning a pusher pole in a manner to distribute the force applied by means of the pole to the explosive and then via the explosive to the walls of the container, while placing the packaged explosive in position at the blast site; and a fuse held within the container by the plate.

The container for the explosive is normally a tube or bag made of a generally flexible sheet material. Plastic films made of polypropylene, polyethylene, polyvinyl, chloride, polyvinylidene chloride, nylon, polyacrylonitrile, polycaprolactam, polyethylene glycol terephthalate (Mylar), polybutadiene, polyurethanes, natural and synthetic rubbers, polyepoxide resins and the like are preferred. However, kraft paper and fabrics made of cotton, burlap, jute, sisal, hemp and the like are also suitable. Multiply composites of the materials specified above can also be used. The package is preferably relatively liquid-impervious when used for explosives containing liquid ingredients, such as Water, or liquid sensitizers and oils, to prevent loss through the walls of the package. If water-pervious materials such as paper, and fabrics are used, they can be coated with a hydrophobic coating material such as a silicone resin. The material of the container should also be relatively strong and abrasion and tear resistant, so that it does not burst or tear when forced into place. The container can be made in any shape, as long as it can accommodate itself to the space limitations normally found at the blast site.

The explosive composition used should be deformable or pliable enough to fit, to the extent permitted by the container, into the space between the boulder and the chute when forced into position. The explosive can be in the form of a powder, a granular composition, a soft gel, a plastic gel, a semisolid slurry, or a relatively thick slurry. Thin slurries or liquid explosives of low viscosity can also be used, if precautions are taken to prevent leakage. An embodiment of this invention particularly suited for such explosive compositions is described below. Any high explosive can be used, such as TNT sensitized ammonium nitrate type slurry high explosives, smokeless powder sensitized ammonium nitrate type slurry high explosives; nitrostarch sensitized ammonium nitrate type slurry high explosives; TNT-ammonium nitrate pellet form solid high explosives and nitrostarch sensitized ammonium nitrate type semi-solid high explosives, nitrocarbonitrates, and nitroglycerine dynamites, such as semi-gelatins, ammonia gelatins and ammonia dynamites of regular or specially desensitized types. Typical explosive composition formulations that are particularly suitable for use in this invention are described hereinafter.

The bottom plate is normally located in the bag at the bottom thereof, and' preferably comprises a relatively thin fiat plate. However, thick plates can also be used. The bottom plate can take generally any shape, and circular, elliptical, or rectangular shapes are suitable. The shape and size of the support plate, however, should correspond to the cross sectional shape of the bag, so that the plate fits relatively tightly against the sides of the bag, analogous to a piston in a cylinder. In this case, the force exerted on the plate by the pole will be distributed to the walls via the mass of explosive above the plate and the explosive will not flow around the edge of the plate in unduly large amounts while the plate is being pushed from beneath by the pole. Unless the explosive is retained on top of the plate, the charge may not be susceptible if being pushed into a tight crevice. Of course, if the crevice is wide, such seepage is no problem.

The plate also receives and positions the pushing pole within the explosive package. This can be done in several ways. One is by providing an aperture shaped to receive the end of the pole, and either engage it snugly, or permit the passage of the pole therethrough. The plate can also be provided with an enclosed aperture, such as a well adapted to receive the end of the pole and provide a bearing surface for the pole end, against which the force required to push the bombing charge into position can be exerted, while preventing the pole from penetrating into the bag. Other means for receiving and positioning the pole such as lugs, guides, clips, clamps, and the like can also be used to receive and position the pole in the plate. It is also possible to provide a flange or several pins on the pusher pole, spaced from the end of the pole, to engage the plate and prevent the pole from passing through the aperture. The pole can be of greater diameter than the aperture, and have a short stub or tapered end of smaller diameter than the aperture, so that only the tapered or stub portion passes through the aperture.

The fuse can also be used to aid in distributing the force applied by the pole, and prevent the pusher pole from being forced through the front end of the container, and this is explained more particularly below. The means for receiving and positioning the pusher pole whether, an aperture, a .well, or other positioning means will normally be centrally positioned on the plate. The support plate can be made from any material; however, polystyrene, polyvinyl chloride, polyethylene, polypropylene, and polycarbonate plastics are preferred. Materials such as cardboard, fiberboard, wood, plywood, and metal also can be used.

It has been found convenient, when an aperture is employed as the positioning means, to provide a series of perforations or weakened portions in the plate in the shape of the desired aperture. When the pusher pole is forced thereagainst, the perforations or weakened portions will give way, and the pole can be inserted through the plate.

In addition, when a plastic plate is used, it is also quite convenient to fabricate the plate as one piece, having either a well or lugs as an integral part thereof.

The fuse is preferably a fuse of the Primacord detonating fuse type. However, other fuse cords of both the defiagrating and detonating type are also suitable.

The plate engages the fuse within the container and holds at least a portion of the fuse adjacent one end thereof in position in the container. This is normally the bottom end into which the pushing pole is inserted. When the package is slit to permit the entry of the pushing pole into the package, the fuse will thus be readily accessible, and preferably exposed, for connection to a downline fuse. Since the connection to the downline fuse is located on the bottom end of the container, below the plate, and protected by the plate, and not at the sides or the front end of the container, it therefore will not abrade against the chute wall and thus, will not become snagged and dislodged when the packaged explosive is jammed into position. The fuse cord is preferably attached to the plate by looping it through several apertures in the plate to form a bail or loop of the fuse cord within the container. When this is done, the free ends of the fuse are tied together in a knot or otherwise joined by a clip or the like. One loop is sufiicient. However, two or more loops are preferred. The knot can itself provide the explosive force to initiate the explosive within the container. However, the knot formed in the fuse cord can be provided, if desired, with a booster explosive such as TNT, pentolite, composition B, or the like, cast or molded into position on the knot, either by dipping the knot in the molten booster explosive, or formed in wad about it.

The fuse need not be attached to the plate by forming a loop and passing it through an aperture in the plate. The fuse can comprise merely a straight length of fuse attached to the plate, by clips, or any other attachment means known to those skilled in the art. When a loop in the fuse cord is used, it can play an important role in transmitting the force applied by means of the pole to the plate, to position the package at the blast site, and prevent the pusher pole from bursting through the front end of the container. This can be accomplished by positioning the knot or other juncture in the fuse cord in line with the aperture in the plate. When the pusher pole is inserted through the aperture in the plate, it will engage the knot. This will in turn, transmit the force applied by the pole to the plate which distributes the force over the mass of explosive. The plate does not move readily through the mass of explosive, if at all, and thus, the pole cannot reach the front end of the container.

The explosive is packaged by first inserting in a container, such as a cylinder or bag of a generally flexible material, the assembly of the plate and the fuse fixed thereto. The container is then filled with a deformable explosive, and sealed. As an alternative, the container can first be partially filled with explosive, and then the plate and fuse placed inside. Any remaining space can then be filled with explosive before the bag is sealed.

When the packaged explosive is to be used, the end of the container in which the plate and the fuse are located is slit and the downline detonating fuse is then tied to the fuse which is accessible at the slit. The pusher pole is then inserted through the slit and is received by the bottom plate. The pole is forced forward until the pole end engages either the knot on the fuse, or the bottom of the well in the plate. The container is then inserted into the crevice and jammed into position between the wall and the boulder. In order to wedge the bag into place, a force is applied to the pusher pole. This force is transmitted to the plate, which, distributes it to the mass of explosive, and this in turn transmits it to the Walls of the container. The plate thereby prevents the pole from reaching and piercing the front end of the bag. The explosive charge is then ready to be detonated.

In the following drawings,

FIGURE 1 is a view in cross section of a packaged explosive in accordance with this invention,

FIGURE 2 is a view similar to that of FIGURE 1 of another embodiment of this invention,

FIGURE 3 is a view similar to that of FIGURE 1 of a third embodiment of this invention, and

FIGURE 4 is a view similar to FIGURE 1 of a fourth embodiment of this invention.

In the embodiment shown in FIGURE 1, a container 2 formed of a polyethylene plastic film encloses a thixotropic semi-solid explosive 3. The explosive is of the following composition.

Percent Nitrostarch (dry) 39.00 NH NO (grained) 31.25 NaNO (grained) 12.00 ZnO 0.80 Flake aluminum 1.75 Solium carboxymethyl cellulose 0.90 Sodium thiosulfate 0.30 H O 14.00

Density: 1.36 g./cc. Detonation velocity: 20,116 ft./sec. D cap sensitivity: 5 grams pentolite This composition is prepared by admixing the various components and is of a thixotropic semi-solid consistency.

At one end of the container a bottom plate 4 is positioned. The bottom plate 4 is provided with a central aperture 5 through which a pusher pole 6 is inserted via a slit 7 in the end of the package. The plate is provided with four apertures 9 through which two loops of detonating cord 10 are positioned. The free ends of the loops are formed into a knot 12 which is aligned with the aperture 5 ofthe plate 4 such that when the pusher pole 6 is inserted through the aperture 5 the knot 12 abuts the end of the pole. Thus, when a force is applied to the pole, it will be transmitted by the cord 10 to the plate, which in turn distributes the force to the explosive, and thence to the walls of the bag. Since neither the pole nor the plate can move forward significantly relative to the bag, the end of the pole cannot pierce the front end of the bag. The loops of detonating cord 10 are connected to a downline fuse 15 by a knot 16 formed just adjacent the pusher pole 6.

The assembly was produced 'by first inserting the assembly of the plate and initiating cord with the knot 12 of the initiating cord generally aligned with the central aperture of the plate 5, in a polyethylene bag. The explosive composition was then poured into place in the package on top of the plate and detonating cord assembly, and the end of the bag was sealed. In order to use explosive package, a slit was formed in the end of the package and the loops of the detonating cord were tied to the downline fuse. The pusher pole was then inserted through the slit and through the central aperture of the plate into the explosive composition until it engaged the knot. The bag was then wedged into position without the pusher pole penetrating the frontend of the bag.

The embodiment shown in FIGURE. 2 is similar to that shown in FIGURE 1 with exception that in this embodiment the plate is made of a polypropylene plastic and is formed with a well 20. The well is of a size sufficient to readily accommodate the end of the pusher pole 6 and provides the surface against which the pole bears when the package is jammed into position. In this embodiment, a peripheral seal 25 can be conveniently formed between the periphery of the plate 4 and the container 2. If the plate and bag are made of thermoplastic material this can be conveniently done by heat sealing. When sealed in this manner, the package can be used for very .thin slurries and liquid explosives of low viscosity. This is possible since the insertion of the pusher pole into the well would not cause leakage of the explosive through the slit 7 in the bag. The only possible place that leakage could occur would be through the apertures in the plate through which the detonating cord is located. These apertures are small and can be made to fit tightly about the detonating cord. Thus, if leakage occurs at all, it will be minimal. The explosive used was of the following composition.

- Per-cent TNT 21.00 NH NO (grained) 60.00 NaNO (coarse) 8.00 Ca'Co .4 Petrolatum .6 Carbonaceous Material 10.00

Density: 1.49 -g./cc. Detonation velocity: 12,000 ft./ sec. D cap sensitivity: No. 1 test cap Detonation volocity: 6,000 ft./sec. D cap sensitivity: No. 2 test cap The explosive composition was prepared by admixing the components and was of granular consistency.

A similar embodiment is shown in FIGURE 4 with the exception that the pusher pole 6 in this instance is provided with a tapered end 29 which engages the central aperture 5 of the support plate 4 to limit the amount to which the pusher pole 6 can be inserted into the bag. The explosive used in each of the two embodiments described immediately above is of the following composition:

Percent NH NO (prills) 94.00 Fuel oil (No. 2) 6.00

Density: .80 g./cc. Detonation velocity: 10,000 ft./sec. (confined) D cap sensitivity: No. 10 test cap (confined) This composition is prepared by admixing the two components. The consistency was that of freely flowing damp granules.

Having regard to the foregoing disclosure, the following is claimed as the inventive and patentable features thereof.

1. A packaged explosive particularly suited for use as a bombing charge and which is positioned at the blast site by use of a pusher pole, comprising, in combination, a generally flexible container; a deformable explosive therein; a force-distributing bottom plate disposed in the container for receiving and positioning a pusher pole; means associated with the plate for engaging the pole in a manner to distribute the force applied by means of the pole to the explosive and then via the explosive to the walls of the container while placing the packaged explosive in position at the blast site; and a fuse held within the container by the plate.

2. A packaged explosive in accordance with claim 1 in which at least a portion of the fuse is held adjacent an end of the container by the plate.

3. A packaged explosive in accordance with claim 1 in which the fuse comprises at least one loop of detonating cord. 4. A packaged explosive in accordance with claim 3 in which a detonating cord is disposed through the bottom plate, and in which the free ends of said detonating cord are joined together.

5. A packaged explosive in accordance with claim 4 in which the cord ends are joined in a knot and the knot is positioned to engage the pusher pole when received by the plate, said knot thereby comprising said means.

6. A packaged explosive in accordance with claim 1 in which the plate has a central well which comprises said means.

7. A packaged explosive in accordance with claim 1 in which the plate has a central aperture.

8. A packaged explosive in accordance with claim 7 in which the means associated with the plate is a central aperture smaller in diameter than a portion of the pusher pole, so that a portion of the pusher pole engages the plate.

9. A packaged explosive in accordance with claim 1 in which the fuse has a booster charge attached thereto.

10. A packaged explosive in accordance with claim 1 in which the container is made of a flexible plastic material.

11. A packaged explosive in accordance with claim 1 in which the container is made of paper.

12. A packaged explosive in accordance with claim 1 in which the explosive is in powder form.

13. A packaged explosive in accordance with claim 1 in which the explosive is in granular form.

14. A packaged explosive in accordance with claim 1 in which the explosive is a semi-solid.

15. A packaged explosive in accordance with claim 1 in which the explosive is a gel.

16. A packaged explosive in accordance with claim 1 in which the plate is made of a plastic material.

17. A packaged explosive in accordance with claim 16 in which the plate is bonded to the container.

18. A packaged explosive in accordance with claim 1 in which the plate is made of cardboard.

19. In combination, a packaged explosive in accordance with claim 7 and a pusher pole disposed through the aperture, and having means adapted to engage the plate, said means being positioned on the pole a distance from the end less than the length of the bag.

20. The combination defined by claim 19 wherein the means on the pusher pole is a flange.

21. A packaged explosive comprising, in combination, a flexible bag, a deformable explosive therein, a plate disposed at the bottom end of the bag, said plate being adapted to receive and position a pusher pole for mounting of the packaged explosive on the pusher pole to place the packaged explosive at the blast site; at least two loops of detonating cord disposed through said plate, said cord having the free ends thereof joined together and said plate retaining at least a portion of said cord in position adjacentthe bottom of the bag; and means associated with one of the plate and the loops of detonating cord, adapted to engage the pusher pole and distribute, via the plate, to the explosive in the bag, and thence to the walls of the bag, the force applied by means of the pole to position the package at the site.

22. A packaged explosive in accordance with claim 21 in which the means is a well in the plate.

23. A packaged explosive in accordance with' claim 21 in which the means is the joined ends of the detonating cord.

References Cited UNITED STATES PATENTS 119,330 9/1871 Dickey 10'221.4 1,571,122 1/1926 Hutton 10226 2,685,836 8/1954 Sauvage l0226 X 2,911,910 11/1959 Welsh 102--24 2,969,101 1/1961 White 10224 X 3,049,079 8/1962 Eilo 102-24 3,208,381 9/1965 Kihlstrom et a1. 10230 3,256,814 6/1966 Kruppenbach et a1. 102-24 FOREIGN PATENTS 117,896 8/1958 U.S.S.R.

VERLIN R. PENDEGRASS, Primary Examiner 

